Most of so-called large or big square balers in use work according U.S. Pat. No. 4,372,104, wherein a pick-up device loads harvested agricultural material into a supply passage, connected to the inlet opening of a baling chamber. A pressing ram is reciprocated back and forth in said horizontally arranged baling chamber or compressing channel by at least one plunger for compacting the material to a big square bale up to a weight of one ton. Usually, the drive assembly of the plunger is a pitman-and-crank-assembly coupled to a gear-box, as disclosed in U.S. Pat. Nos. 4,275,550 or 4,604,858 or 4,782,651 or 4,525,991, respectively. These drive means are rather voluminous and have many components thus being relatively expensive to produce.
A similar crop baler is disclosed in U.S. Pat. No. 4,157,643, wherein the agricultural material is moved through the supply passage to the baling chamber by a stuffing or feeding device extending into the supply passage with a plurality of fork-like fingers or tines. The crop entering the compressing channel is only low compressed by the tines of a packer. Actuation of the plunger and the stuffing fork occurs in response to obtaining a predetermined density of the accumulated charge as sensed by a pressure-sensitive device on the loading duct. However, the predensification remains rather low; thus, the plunger has to reciprocate along a way which is at least two times greater than the width of the feeding duct. Thus the main compacting work has to be done by said pressing ram, which has to be very heavy dimensioned. Furthermore, the drive means of the feeding mechanism is rather complicated, as this crop baler needs a loader separate from said packer to stuff the precompressed charge into the baling chamber.
As the agricultural material has a certain elasticity when compressed, the compressed material reexpands in the baling chamber upon the return movement of the reciprocating ram. Thus, with this method the material is compressed several times causing a loss of energy and the degree of compression is relatively low due to the reexpansion of the material.
The German Patent No. 34 45 015 discloses a rotary compressing drum with tines, the tips of which engage grooves in the drum casing, thus shredding and crushing the material. In this way a densified layer is produced, which is accumulated in a box to a rectangular bale.
Although the degree of compression is higher than with the above-mentioned usual big balers, it is desirable to improve the density to achieve highly densified bales which may be transported and stored with minimum space.
Furthermore, the forming of a rectangular bale according to the German Patent No. 34 45 015 is very complicated, as the layers are piled up in a generally vertical box by lowering the groundplate of this box step-by-step. Thus, the size of the accumulated bale is very difficult to change. After forming one big bale consisting of about ten to twenty layers the groundplate has to be lifted in only a few seconds, as the feeding of the material is continuous. As the doors of the box have to be opened and the knotting device has to be operated by a very complicated hydraulic control circuit. Thus, continuous, fast operation of the crop-baler is very difficult to achieve. The same is true for the loading apparatus of above-mentioned U.S. Pat. No. 4,157,643, as the stuffing fork must be operated very rapidly during retracting movement of the plunger in order to assure completely stuffing as described in said patent. Consequently, the drive means have to be rather complicated to achieve said rapid charging stroke by means of a clutch device with several springs, sprockets and projections, which may wear out because of frequent actuation.
It is a primary object of the invention to provide a crop baler for harvesting of agricultural material, achieving a high compression without reexpansion of the bale.
It is further object of the invention to provide a compact design of the baler and simple drive means having a small number of components.
Still another object of the invention is to provide a baler allowing continuous, fast operation in the field.
These and other objects are obtained by a crop baler for harvesting of field-fodder like hay, straw, grass-silage and forming substantially rectangular bales thereof in a baling chamber comprising pick-up means for picking up the field-fodder from the ground; a compressing drum rotating in a drum casing and provided with tines for shredding and crushing the field-fodder picked up by said pick-up means to a highly densified layer; a press channel forming an output of the compression drum, having a slotted portion for permitting passage of said tines and conveying said layer formed in said compression drum by further densifying said layer through an inlet opening into said baling chamber; a compressing plate arranged at an end surface of said baling chamber and reciprocatable in said baling chamber by a distance approximately corresponding to the width of said press channel for pressing said layers accumulating in said baling chamber in said direction toward an discharge opening of said baling chamber; and a detector means arranged near an upper side of said baling chamber for initializing said reciprocating movement of said compressing plate upon arrival of said layer at said upper side of said baling chamber.
As the result of this crop baler according the invention the already densified layer is further compressed and compacted at its flat side thus increasing the degree of density of the rectangular bale. Since the agricultural material fed into the baling chamber is already highly pre-densified by the compressing drum and the press channel the drive means of the compressing plate may be designed simple and less strong. By further compressing the layer at its flat or main side a reexpansion is avoided, since in contrast to the known big balers the crop material is not loosely fed into the baling chamber but as a high-densified layer. In contrast to the apparatus of the German Patent No. 34 45 015 the dimensions of the rectangular bale, especially the length of the bale may be easily changed by varying the number of compressed layers.
With this crop baler it is not necessary to use haydogs or the like as they are used in connection with the bale chamber in U.S. Pat. No. 4,782,651 for holding a freshly compacted charge of material against retrograde movement after being pressed rearwardly by the plunger, because the highly densified layer which is cut off near the inlet opening does not reexpand.
Due to this structure the layers and the resulting rectangular bale remain well shaped and form fitting, thus enabling a high degree of compression achieved with low energy.
In a preferred embodiment the main compression by the tine-drum arrangement is very high, so that the layer in the press-channel will not be compressed in longitudinal direction anymore. To enable a continuous operation of the crop baler during the forward movement of compressing-plate into the baling chamber there is provided a slotted lateral wall, which is displaceable in a longitudinal direction of that press channel, thus interrupting the supply of the high-densified layer to the press channel by the compressing-drum.